The binding of metal ions, (copper and nickel, in particular) to albumin from different animal species was studied using different physical techniques. The action of D-pencillamine, a copper mobilizing drug, on copper binding to HSA was studied. HSA was labeled with fluorescent labels. In addition, studies are being carried out with synthetic peptide and chemical and enzymatic fragments of HSA. Attempts will be made to characterize the copper binding sites, in addition to the N-terminal site.